The present invention relates to a method for estimating the duration of a battery performance rehabilitation phase, the latter being able to be a battery charging phase.
The invention applies preferentially to a traction battery of a hybrid vehicle equipped with a hybrid power train, comprising a heat engine and at least one electrical machine intended to ensure, together or independently, the provision of a torque at the wheels of the vehicle. The invention applies in a non-limiting manner to a traction battery implemented in a hybrid power train architecture requiring, in a launch or “take-off” phase from stopped and at low speeds of displacement of the vehicle, the power supplied at the wheels to originate exclusively from the vehicle traction battery. Such is the case in certain architectures where, by construction, the heat engine can be involved in the propulsion of the vehicle only for a predetermined target vehicle speed, such that the power train has only the electrical energy stored in the traction battery of the vehicle to ensure the starting and the displacement of the vehicle until said predetermined target vehicle speed is reached, at which point the heat then cuts in.
In this type of architecture, to avoid a temporary immobilization of the vehicle, the traction battery must therefore always be able to supply a required minimum power level making it possible to ensure the take-off of the vehicle. At any instant, the discharging power available on the battery depends on its state of charge (the more discharged the battery, the less power it will be able to supply), on its temperature (the colder the battery, the less power it will be able to supply) and its state of aging (the older the battery, the less power it will be able to supply). Also, in practice, it is best to ensure that the battery always remains at a minimum state-of-charge level and at a minimum temperature level enabling it to ensure the required minimum power level. To do this, it is known practice to use an energy management law in the computer dedicated to battery management, making it possible to order the recharging of the battery as soon as it is too discharged, for example when its state-of-charge falls below a critical threshold, either by the activation of a regenerative braking system, or by the activation of a generator system which is itself driven by the heat engine of the vehicle. The energy management law can also be designed to make it possible to limit the power supplied by the traction battery when its state of charge becomes close to a minimum threshold below which it can no longer ensure the required minimum power level.
In certain extreme cases of use, the energy management law applied by the computer does not however make it possible to maintain the battery in conditions enabling it to ensure the required minimum power level. The vehicle is then potentially in a situation of temporary immobilization, in which the traction battery is incapable of supplying the required traction power to ensure the take-off of the vehicle from stopped and at low speeds of displacement of the vehicle.
The patent document FR2992274, in the name of the applicant, discloses a method for controlling the recharging of a hybrid vehicle traction battery equipped with a hybrid power train exhibiting the limitations as explained above, this method providing, on forced stopping of the vehicle, for the heat engine to drive the electrical machine operating in generator mode to recharge the battery, while the starting of the vehicle is purely and simply refused until the state of charge of the battery has gone back above a threshold enabling it to supply the required minimum power level.
A drawback of this system is that the vehicle is blocked until the traction battery performance is rehabilitated, in other words until the latter reverts to state-of-charge and temperature conditions enabling it to supply the required minimum power level. The immobilizing of the vehicle on the road may indeed be temporary, but it nevertheless places the driver in an uncomfortable and anxious situation, not knowing the battery performance rehabilitation time after which the required minimum power can be supplied in order to restart the vehicle.
Also, there is a need to be able to obtain an accurate estimation of the duration of this battery performance rehabilitation phase and, in particular, to be able to estimate the duration of a charging phase of a traction battery of a hybrid vehicle activated when stopped to bring this battery to state-of-charge and temperature conditions enabling it to supply a required minimum power level.